Nebulizer

ABSTRACT

A disposable nebulizer device for producing aerosol includes an enclosed container having an aerosol outlet, a nozzle assembly extending into the container, and a diffuser-baffle assembly in the container. The nozzle assembly includes a gas nozzle and a spray nozzle with spaced and coaxially positioned orifices. The diffuser-baffle assembly is located in the spray path of the spray orifice and includes a nose portion which extends towards the orifices and is coaxially positioned therewith.

Oct. 2, 1973 United States Patent 1 Lester 3,580,249 5/l97l Takaoka l28/l94 NEBULIZER Primary Examiner-Richard A. Gaudet Assistant ExaminerG. F. Dunne Attorney-Lyon & Lyon [22] Filed:

[21] Appl. No.: 86,525

ABSTRACT A disposable nebulizer device for producing aerosol includes an enclosed container having an aerosol outlet, a nozzle assembly extending into the container, and a diffuser-baffle assembly in the container. The nozzle assembly includes a gas nozzle and a spray nozzle with spaced and coaxially positioned orifices. The diffuserbaffle assembly is located in the spray path of the spray orifice and includes a nose portion which extends to- 80 8 X nm92fl 4 11 5 9 8 4 n 82 8 4m n 2 t 4 4 9....7 S u 9 "12 T n 3 /.9 n 2 8 N m Q E m n 4 Tu 9 CA 1 t mn M 2 m S m I. SE 4 e k nnn CT a num, A n mmufl NT 0 n s .NSD nflh4 e not! .r/ E8 "38 T5 e on m ma n .d S ud 7 I i l. 0 HIM u 555 5 [[il 2 wards the orifices and is coaxially positioned therewith.

3,097,645 7/l963 Lester..... l28/l94 3,172,406 3/1965 Bird 128/194 20 Claims, 5 Drawing Figures NEBULIZER This invention relates to a new and improved liquid nebulizing device and more particularly relates to adisposable, preferably plastic, nebulizer having improved aerosol production.

Nebulizers are pneumatic devices for breaking up a liquid medicament into small particles and to entrain the small liquid particles in the stream of air or gas thereby providing an aerosol for inhalation therapy in the treatment of respiratory system disorders. It is important during such thereapy that there be a sufficient quantity and proper formation of aerosol provided by the nebulizer. If the particles or droplets of the medicament are too fine, they are not likely to be retained in the respiratory tract, but will, to a great extent, be exhaled. If the particles are too large, they will likely be deposited on the upper reaches of the respiratory system, such as the trachea and the upper trachealbronchial tree, thereby leaving the rest of the system untreated. It is also important that the aerosol be delivered to the patient in a smooth, uniform manner.

Production of a proper aerosol is substantially dependent on the design of the nebulizer. Prior to my U.S. Pat. No. 3,097,645, it was conventional to employ the fly-spray principle of aerosol in the design of nebulizers. This principle involves directing a stream of gas from a nozzle at right angles across the open end of a tube running to the liquid medicament. Proper positioning and sizing of the tube and nozzle are extremely critical and the design of a nebulizer employing this principle is such that it is difficult and expensive to manufacture, particularly if the nebulizer is to be made of plastic.

Often fly-spray nebulizers are made of glass and therefore are very delicate and must be handled with a great degree of care. However, because of the relatively high cost of such nebulizers it is not practical to dispose of them after use and therefore these nebulizers must undergo periodic cleaning. This cleaning process is expensive and in addition frequently results in breakage.

On the other hand, a nebulizer of the type shown in my previously referred to U.S. Pat. No. 3,097,645 is simple and inexpensive to manufacture. Also, the design of this type nebulizer is such that the device can be easily formed of plastic and the device is relatively unbreakable. Moreover, because this type nebulizer can be produced at a marked reduction in cost, the entire nebulizer can be disposed of after use thereby avoiding the costs of cleaning. The present invention represents an improved form of this particular type of nebulizer and employs certain elements of this nebulizer. However, the present invention also includes numerous details of construction not shown in any previous nebulizer devices which produce new and improved results.

It is therefore a primary, object of this invention to provide a nebulizer having improved aerosol production and improved operating characteristics. In accordance with this and other objects, the nebulizer of the present invention includes a container having a aerosol outlet, a nozzle assembly extending into the container having a gas orifice and a spray orifice spaced from and coaxial with the gas orifice, and a diffuser-baffle assembly positioned within the container in the spray path of the spray orifice. When gas is passed through the gas orifice liquid is drawn from the container into the space between the orifices and then carried in the form of small particles through the spray orifice. The spray nozzle is provided with a recessed portion on its outer surface surrounding the spray orifice to minimize noise created by the spray. A nose portion of the diffuserbaffle assembly extending towards the spray orifice and concentric therewith provides for improved performance and a baffle plate prevents oversize liquid particles from passing out through the aerosol outlet.

Another object of this invention is to provide a plastic disposable nebulizer which is simple and inexpensive to manufacture.

Other objects and advantages of this invention will be apparent from the following description and accompanying drawings.

In the drawings:

FIG. 1 is a side sectional view of the nebulizer.

FIG. 2 is a cross-sectional view taken substantially on the lines 22 of FIG. 1 illustrating the nozzle assembly.

FIG. 3 is a cross-sectional view taken substantially on the lines 3-3 of FIG. 1 illustrating the liquid inlet means of the spray nozzle.

FIG. 4 is a cross-sectional view taken substantially on the lines 44 of FIG. 1.

FIG. 5 is a cross-sectional view illustrating the respective positioning of the gas orifice, spray orifice and nose portion of the diffuser-baffle assembly.

Referring now in detail to the drawings, the nebulizer device, generally designated 10, is preferably constructed of a'plastic material such as crystal polystyrene and includes essentially four separately molded components, an aerosol outlet component 11, a cover component 12 including the diffuser-baffle assembly, a bowl component 13 including the spray nozzle, and a gas nozzle component 14. Because of their shape, each components may quickly and easily be injectionmolded and then assembled without the need for extensive additional machining.

The aerosol outlet component 1 1 comprises a slightly tapered, tubular member 15 having proximate its lower end a circumfenential flange 16 which forms a shoulder 17. The cover component 12 includes a cylindrical sidewall 18 which terminates at its upper end in an annular flange 19 forming a central opening 20. The lower end of the aerosol outlet component 11 fits into the opening 20 with the shoulder 17 abutting the flange 19. The upper end of the aerosol outlet component 11 may be adapted to fit into a conventional inhalation mask or other device for attaching the unit to the patient or it may be used as a mouthpiece which is inserted into the mouth of the patient.

The bowl component 13 is generally cup shaped with the lower portion of the bowl narrowing down and the upper portion forming a generally cylindrical sidewall which is adapted to join at its upper end 21 the lower end 22 of the cylindrical sidewall 18. An interlocking V-tongue 23 and V-groove 24 are provided on the lower end 22 and the upper end 21, respectively, to insure proper alignment of the bowl and cover components. Together, the bowl component 13 and the cover component 12 form a container, generally designated 25, having a smooth inner surface 26 which defines a mixing area 27 in the upper portion of the container 25 and a reservoir area 28 in the lower portion of the container 25. The reservoir 28 is adapted to hold about 8 cubic centimeters of liquid medicament and the mixing area is of sufficient volume to minimize the attractive action of the plastic material for the droplets of medicament which otherwise might interfere with the operation of the nebulizer.

The bowl component 13 is also provided with a central opening 29 at its lower end. The edge 30 of the opening 29 includes three inwardly extending, integrally formed ribs 31 and the outer surface of the bowl surrounding the opening 29 defines a flat cylindrical collar 32. The gas nozzle component 14 extends into the opening 29 and includes a shoulder 33 proportioned to seat upon the collar 32. The shoulder 33 is relatively wide to provide a sturdy, firm support for the nozzle component 14 at the collar 32 and the three ribs 31 assist in properly positioning the gas nozzle component 14.

During assembly the aerosol outlet component 11, the cover component 12, the bowl component 13, and the gas nozzle component. 14 are joined together by a suitable means, preferably by an ultra-sonic sealing process, to form a durable unit. The nozzle assembly, generally designated 34 includes a spray nozzle 35 which is an integrally molded element of the gas nozzle component 14. The spray nozzle 35 extends upwardly from the lower end of the inside surface of the bowl component 13 and is slightly tapered and tubular in form. The upper end of the spray nozzle 35 curves inwardly to form an end wall or annular flange 37 with a centrally positioned round spray orifice 38. The outer surface 39 of the end wall 37 is provided with a frustoconical recess 40 which is coaxial with and surrounds the spray orifice 38. At the lower end of the spray nozzle 35 is a series of liquid inlets 41, equally spaced around the base of the spray nozzle 35, and communicating with the reservoir 28 so that liquid medicament may flow unrestricted into the inside of the spray nozzle 35.

In determining the diameter of the spray orifice 38, consideration must be given to the rate of gas flow through the nebulizer and the viscosity of the liquid medicament to be nebulized. When used with a gas flow of between about 3 to 8 liters per minute and a thin liquid with a viscosity approximately that of water, a spray orifice 38 having a diameter within the range of about 0.036 and 0.042 inch produces a satisfactoryaerosol. If the gas flow rate is extended outside this range, and/or a more viscous liquid is used, then compensation should be made in the diameter of the spray orifice 38 to obtain the desired aerosolization.

Also of importance is the distance between the inner surface 42 of the end wall 37 and the outer surface 39 of the end wall 37 at the edge 43 of the orifice 38. In accordance with the gas flow and the liquid viscosity set forth above it has been found that a distance of about 0.015 inch is preferable to prevent noise when spray eminates from the spray orifice 38. This distance at the edge 43 of the spray orifice 38 is achieved by the recess 40 while still permitting injection molding of the end wall 37.

The size of the liquid inlets 41 are not as critical. Substantially any opening which will permit sufficient flow of liquid from the reservoir 28 into the inside of the spray nozzle 35, to manitain a constant full supply of liquid at the top of the air nozzle 36, will suffice.

As stated previously the gas nozzle 36 is an integrally molded element of the gas nozzle component 14 and it extends upwardly from the shoulder 33. The gas nozzle component 14 serves as an inlet for the carrier gas which is normally compressed air or oxygen and therefore is also provided with a connector element 44 which extends downwardly from the shoulder 33 and is adapted to be secured to a flexible hose or other suitable means for communicating the gas to the gas nozzle component 14. The gas nozzle 36 is also slightly tapered from bottom to top, to conform generally with the taper of the spray nozzle 35, and terminates at its upper end in an end wall or annular flange 45 having a centrally positioned orifice 36. The gas nozzle component 14 is also provided with a gas inlet passage 47 which extends from the lower end of the connector element 44 to the gas orifice 46. A check valve 48 positioned within the gas inlet passage 47, permits the upward flow of gas through the inlet passage 47, but prevents a back flow of liquid from the container from passing out through the gas inlet passage 47.

When the gas nozzle 36 is inserted into place inside the spray nozzle 35, the gas orifice 46 and the spray orifice 38 are coaxial and spaced apart a predetermined distance. The space between the gas orifice and the spray orifice is properly determined and maintained by the seating of the shoulder 33 with the collar 32. The coaxial relationship of the orifices is properly determined and maintained by the ribs 31 engaging an annular flange 49 at the lower end of the gas nozzle 36 and by three other integrally formed and equally spaced ribs 50 of the spray nozzle 35. The ribs 50 extend radially inward from the inner surface 51 of the sidewall 52 of the spray nozzle 35 and engage the outer surface 53 of the sidewall 54 of the gas nozzle 36 proximate the upper end of the gas nozzle 36.

The inner surface 51 and the outer surface 53 of the sidewalls 52 and 54, respectively, of the nozzles and the inner surface 42 and the outer surface 55 of the end walls 37 and 45, respectively, of the nozzles also define a passage 56 which extends from the liquid inlets 41 through the space between the ribs 50 to the space between the orifices 38 and 46.

As with the spray orifice 38, there is a relationship between the diameter of the gas orifice 46, the gas flow rate, and the viscosity of the liquid. Based upon a gas flow of from 3 to 8 liters per minute, and a thin liquid with a water like viscosity, the diameter of the gas orifice 46 should be between about 0.024 and 0.028 inch. Where gas flow rates outside of this range are used, and/or more viscous liquids are to be nebulized, the diameter of the gas orifice 46 should be altered to that providing the desired result.

Along with the foregoing relationships, for satisfactory results the distance between the inside surface 42 of the end wall 39 of the spray nozzle 35 and the outside surface 55 of the end wall 45 of the gas nozzle 36 at the space betwen the orifices should be between about 0.012 and 0.015 inch, where the diameter of the spray orifice 38 is between about 0.036 and 0.042 inch, and the diameter of the gas orifice 46 is between about 0.024 and 0.028 inch. If this distance is greater than about 0.015 inch large droplets are produced instead of a fine aerosol.

The diffuser-baffle assembly, generally designated 57, is an integrally formed element of the cover component 12. The diffuser-baffle assembly 57 includes a circular baffle plate 58 having approximately the same diameter as the lower open end 59 of the aerosol outlet component 11. The baffle plate 58 is supported by three equally spaced legs 60 depending from the inside surface of the annular flange 19 of the cover component 12 adjacent the edge of the opening 20. The baffle plate 58 assists in separating from the aerosol spray emanating from the spray orifice 38 the coarser drops, so that only a fine aerosol fiows around the edge of the baffle plate 58 through the aerosol outlet to the patient. The large separated droplets that strike the baffie plate 58 drop back into the liquid in the reservoir 28. The underside surface 61 of the baffle plate includes a generally centrally positioned diffuser member 62 extending downwardly therefrom. The downwardly extending lower end of the diffuser member 62 comprises a nose portion 64 spaced from the spray orifice 38 with the furthermost downward extension 65 of the nose portion 64 extending about 0.030 inch from the spray orifice 38 and being coaxial therewith. The nose portion 64 includes a generally rounded surface of revolution 66 diverging from the furthermost extension 65 away from the spray orifice 38 thereby defining a path 67 for the aerosol spray emanating from the spray orifice 38 between the surface of the recess 40 and the surface of the nose portion 64.

In operation, the reservoir 28 of the nebulizer is filled to a level below the top of the spray nozzle 35 with a liquid medicament or theraputic. A suitable source of compressed gas is communicated to the gas nozzle 36 by a suitable conduit (not shown) attached to the connector member 44 and the outer end of the aerosol outlet 11 is attached to a mask covering the patients face.

As gas courses upwardly through the gas nozzle 36 and exits through the gas orifice 46, it creates a partial vacuum in the space between the orifices 46 and 38. This vacuum causes the level of the liquid medicament in the passage 56 between the nozzles 35 and 36 to rise and flow over the top of the nozzle 36. When the stream of gas strikes this liquid it entrains it in droplet form and carries it along upwardly through the spray orifice 38 and then through the path 67 which promotes aerosolization. The spray then continues upward where a substantial portion strikes the underside surface 61 of the baffle plate 58 to remove oversize droplets of liquid. After the oversize droplets are removed, the aerosol spray eventually migrates around the edge of the baffle plate 58 through the aerosol outlet component 11 and then on into the patient's respiratory tract. Since the bottom portion of the reservoir area 28 tapers down to a narrow confine at the inlets 41, substantially all of the liquid medicament is used before replenishing is necessary.

This invention provides an inexpensive to manufacture, durable nebulizer which because of its low cost of production may be disposed of after use. The nozzle assembly and the diffuser-baffle assembly of the nebulizer minimize noise during operation, provide for proper control of the liquid medicament particles in the aerosol and promote improved aerosolization.

Having fully described my invention, it is to be understood that 1 do not wish to be limited to the details herein-set forth, but my invention is of the full scope of the appended claims.

1 claim:

1. A nebulizer for converting liquid into comprising;

a housing having a liquid reservoir and an outlet opening through which aerosol passes;

aerosol,

a spray nozzle having an end wall defining an orifice and having liquid inlet means in communication with said reservoir;

a gas nozzle positioned within said spray nozzle having gas inlet means and an orifice spaced from and co-axial with said spray orifice;

said spray nozzle and said gas nozzle defining a passage therebetween extending from said liquid inlet means to said space between said orifices;

a diffuser having a nose portion spaced from and adjacent said orifices with the furthermost extension of said nose portion coaxial with said orifices, said nose portion having a surface or revolution diverging from said furthermost extension away from said orifices; and

said end wall having an outer surface extending outwardly from said spray orifice in a direction substantially parallel to the diverging surface of said nose portion with said outer surface of said end wall and said diverging surface of said nose portion defining a narrow path through which spray passes from said spray orifice.

2. The nebulizer of claim 1, wherein the distance between the outer surface and the inner surface of said spray nozzle at the edge of said spray orifice is about 0.015 inch to minimize noise.

3. The nebulizer of claim 1, wherein said spray orifice is defined by an end wall of said spray nozzle, said end wall having a recess coaxial with said spray orifice on the outer surface of said end wall to reduce the thickness of said end wall at the edge of said spray orifice'to prevent noise while permitting injection-molding of said end wall.

4. The nebulizer of claim 1, wherein the distance between said furthermost extension of said nose portion and said spray orifice is about 0.030 inch.

5. The nebulizer of claim 1, wherein the distance between the inner surface of said end wall of said spray nozzle and the outer surface of said end wall of said gas nozzle'at said space between said orifices is between about 0.012 inch and 0.015 inch.

6. The nebulizer of claim 1, wherein the distance between the'inner surace of said end wall of said spray nozzle and the outer surface of said end wall of said gas nozzle in said passage is less than the diameter of said spray orifice.

7. The nebulizer of claim 1, wherein a baffle plate is provided, said baffle plate being positioned in the path of spray emanating from said spray orifice and adjacent said aerosol outlet to prevent oversize droplets of liquid from escaping the nebulizer.

8. The nebulizer of claim 1, wherein said gas inlet means is provided with a check valve to prevent a back flow of liquid through said gas nozzle. I

9. The nebulizer of claim 1, wherein the inner surface of said end wall extending from said spray orifice is parallel to the outer surface of said end wall extending radially from said gas orifice.

10. A nebulizer for converting liquid into aerosol,

compressing;

an enclosed container having a liquid supply reservoir and an aerosol outlet;

a nozzle assembly extending into said container including an inner gas nozzle and an outer spray nozzle encircling said gas nozzle;

said gas nozzle having an end wall defining a gas orifice and said spray nozzle having an end wall defining a spray orifice spaced from and coaxial with said gas orifice;

said end walls having a passage therebetween extending to said space between said orifices;

said gas nozzle having a gas inlet means in communication with said gas orifice and said spray nozzle having liquid inlet means in communication with said reservoir and said passage;

a diffuser in said container having a nose portion adjacent said orifices with the furthermost extension of said nose portion sapced from and coaxial with said spray orifice, said nose portion having a surface of revolution diverging from said furthermost extension away from said spray orifice; and

said end wall of said spray nozzle having an outer surface extending outwardly from said spray orifice in a direction substantially parallel to said diverging surface of said nose portion with said outer surface of said end wall and said diverging surface of said nose portion defining a narrow path through which spray passes from said spray orifice.

11. The nebulizer of claim 10, wherein the outer surface of said end wall of said spray nozzle is provided with a recess coaxial with and surrounding said spray orifice.

12. The nebulizer of claim 11, wherein saidnose portion of said diffuser extends into said recess.

13. The nebulizer of claim 10, wherein the distance between said furthermost extension of said nose portion and said spray orifice is about 0.030 inch.

14. The nebulizer of claim 10, wherein the distance between the inner surface of said end wall of said spray nozzle and the outer surface of said end wall of said gas nozzle at said space between said orifices is between about 0.012 inch and 0.015 inch.

15. The nebulizer of claim 10, wherein the diameter of said gas orifice is between about 0.024 inch and 0.028 inch and the diameter of said spray orifice is between about 0.036 inch and 0.042 inch.

16. The nebulizer of claim 10, wherein the distance between the inner surface of said end wall of said spray nozzle and the outer surface of said end wall of said gas nozzle in said passage is less than the diameter of said spray orifice.

17. The nebulizer of claim 10, wherein a baffle plate is provided, said baffle plate being positioned in the path of spray emanating from said spray orifice and adjacent said aerosol outlet to prevent oversize droplets of liquid from escaping the nebulizer.

18. The nebulizer of claim 10, wherein said gas inlet means is provided with valve means to prevent a back flow of liquid passing through said gas nozzle.

19. The nebulizer of claim 10, wherein the inner surface of said spray nozzle is provided with at least three ribs engaging the outer surface of said gas nozzle to position and maintain said gas orifice with respect to said spray orifice.

20. A disposable, preferably plastic nebulizer unit for converting liquid medicament into aerosol, comprising:

four separately molded components comprising an outlet component, a cover component, a bowl component, and a gas nozzle component;

said outlet component having an aersol outlet end, an

aerosol inlet end, and an aerosol passageway therebetween; said cover component and said bowl component each having sidewalls connected together at one end, said sidewalls together defining a container having an upper mixing area and a lower reservoir area;

said gas nozzle component and said bowl component being connected together with a section of said gas nozzle component extending into said container, said gas nozzle component having a gas orifice inside said container and a gas inlet end outside said container in communication with said gas orifice;

said bowl component having an integral spray nozzle within said container, said spray nozzle having an end wall defining an orifice and liquid inlet means in communication with said reservoir area and said spray orifice, said spray orifice being positioned above said reservoir area and spaced from and coaxial with said gas orifice;

said cover component being connected to said aerosol inlet end and having an outlet opening for communication of aerosol between said mixing area and said aerosol inlet end, said cover component further including an integral diffuser-baffle assembly positioned within said container between said outlet opening and said coaxial orifices; and

said diffuser-baffle having a nose portion spaced from and adjacent said orifices with the furthermost extension of said nose portion coaxial with said orifices, said nose portion having a surface or revolution diverging from said futhermost extension away from said orifices; and

said end wall having an outer surface extending outwardly from said spray orifice in a direction substantially parallel to the diverging surface of said nose portion with said outer surface of said end wall and said diverging surface of said nose portion defining a narrow path through which spray passes from said spray orifice. 

1. A nebulizer for converting liquid into aerosol, comprising; a housing having a liquid reservoir and an outlet opening through which aerosol passes; a spray nozzle having an end wall defining an orifice and having liquid inlet means in communication with said reservoir; a gas nozzle positioned within said spray nozzle having gas inlet means and an orifice spaced from and co-axial with said spray orifice; said spray nozzle and said gas nozzle defining a passage therebetween extending from said liquid inlet means to said space between said orifices; a diffuser having a nose portion spaced from and adjacent said orifices with the furthermost extension of said nose portion coaxial with said orifices, said nose portion having a surface or revolution diverging from said furthermost extension away from said orifices; and said end wall having an outer surface extending outwardly from said spray orifice in a direction substantially parallel to the diverging surface of said nose portion with said outer surface of said end wall and said diverging surface of said nose portion defining a narrow path through which spray passes from said spray orifice.
 2. The nebulizer of claim 1, wherein the distance between the outer surface and the inner surface of said spray nozzle at the edge of said spray orifice is about 0.015 inch to minimize noise.
 3. The nebulizer of claim 1, wherein said spray orifice is defined by an end wall of said spray nozzle, said end wall having a recess coaxial with said spray orifice on the outer surface of said end wall to reduce the thickness of said end wall at the edge of said spray orifice to prevent noise while permitting injection-molding of said end wall.
 4. The nebulizer of claim 1, wherein the distance between said furthermost extension of said nose portion and said spray orifice is about 0.030 inch.
 5. The nebulizer of claim 1, wherein the distance between the inner surface of said end wall of said spray nozzle and the outer surface of said end wall of said gas nozzle at said space between said orifices is between about 0.012 inch and 0.015 inch.
 6. The nebulizer of claim 1, wherein the distance between the inner surace of said end wall of said spray nozzle and the outer surface of said end wall of said gas nozzle in said passage is less than the diameter of said spray orifice.
 7. The nebulizer of claim 1, wherein a baffle plate is provided, said baffle plate being positioned in the path of spray emanating from said spray orifice and adjacent said aerosol outlet to prevent oversize droplets of liquid from escaping the nebulizer.
 8. The nebulizer of claim 1, wherein said gas inlet means is provided with a check valve to prevent a back flow of liquid through said gas nozzle.
 9. The nebulizer of claim 1, wherein the inner surface of said end wall extending from said spray orifice is parallel to the outer surface of said end wall extending radially from said gas orifice.
 10. A nebulizer for converting liquid into aerosol, compressing; an enclosed container having a liquid supply reservoir and an aerosol outlet; a nozzle assembly extending into said container including an inner gas nozzle and an outer spray nozzle encircling said gas nozzle; said gas nozzle having an end wall defining a gas orifice and said spray nozzle having an end wall defining a spray orifice spaced from and coaxial with said gas orifice; said end walls having a passage therebetween extending to said space between said orifices; said gas nozzle having a gas inlet means in communication with said gas orifice and said spray nozzle having liquid inlet means in communication with said reservoir and said passage; a diffuser in said container having a nose portion adjacent said orifices with the furthermost extension of said nose portion sapced from and coaxial with said spray orifice, said nose portion having a surface of revolution diverging from said furthermost extension away from said spray orifice; and said end wall of said spray nozzle having an outer surface extending outwardly from said spray orifice in a direction substantially parallel to said diverging surface of said nose portion with said outer surface of said end wall and said diverging surface of said nose portion defining a narrow path through which spray passes from said spray orifice.
 11. The nebulizer of claim 10, wherein the outer surface of said end wall of said spray nozzle is provided with a recess coaxial with and surrounding said spray orifice.
 12. The nebulizer of claim 11, wherein said nose portion of said diffuser extends into said recess.
 13. The nebulizer of claim 10, wherein the distance between said furthermost extension of said nose portion and said spray orifice is about 0.030 inch.
 14. The nebulizer of claim 10, wherein the distance between the inner surface of said end wall of said spray nozzle and the outer surface of said end wall of said gas nozzle at said space between said orifices is between about 0.012 inch and 0.015 inch.
 15. The nebulizer of claim 10, wherein the diameter of said gas orifice is between about 0.024 inch and 0.028 inch and the diameter of said spray orifice is between about 0.036 inch and 0.042 inch.
 16. The nebulizer of claim 10, wherein the distance between the inner surface of said end wall of said spray nozzle and the outer surface of said end wall of said gas nozzle in said passage is less than the diameter of said spray orifice.
 17. The nebulizer of claim 10, wherein a baffle plate is provided, said baffle plate being positioned in the path of spray emanating from said spray orifice and adjacent said aerosol outlet to prevent oversize droplets of liquid from escaping the nebulizer.
 18. The nebulizer of claim 10, wherein said gas inlet means is provided with valve means to preVent a back flow of liquid passing through said gas nozzle.
 19. The nebulizer of claim 10, wherein the inner surface of said spray nozzle is provided with at least three ribs engaging the outer surface of said gas nozzle to position and maintain said gas orifice with respect to said spray orifice.
 20. A disposable, preferably plastic nebulizer unit for converting liquid medicament into aerosol, comprising: four separately molded components comprising an outlet component, a cover component, a bowl component, and a gas nozzle component; said outlet component having an aersol outlet end, an aerosol inlet end, and an aerosol passageway therebetween; said cover component and said bowl component each having sidewalls connected together at one end, said sidewalls together defining a container having an upper mixing area and a lower reservoir area; said gas nozzle component and said bowl component being connected together with a section of said gas nozzle component extending into said container, said gas nozzle component having a gas orifice inside said container and a gas inlet end outside said container in communication with said gas orifice; said bowl component having an integral spray nozzle within said container, said spray nozzle having an end wall defining an orifice and liquid inlet means in communication with said reservoir area and said spray orifice, said spray orifice being positioned above said reservoir area and spaced from and coaxial with said gas orifice; said cover component being connected to said aerosol inlet end and having an outlet opening for communication of aerosol between said mixing area and said aerosol inlet end, said cover component further including an integral diffuser-baffle assembly positioned within said container between said outlet opening and said coaxial orifices; and said diffuser-baffle having a nose portion spaced from and adjacent said orifices with the furthermost extension of said nose portion coaxial with said orifices, said nose portion having a surface or revolution diverging from said futhermost extension away from said orifices; and said end wall having an outer surface extending outwardly from said spray orifice in a direction substantially parallel to the diverging surface of said nose portion with said outer surface of said end wall and said diverging surface of said nose portion defining a narrow path through which spray passes from said spray orifice. 